www.brinno.com / Defective items, but the seller hasn't change them

I bought motion sensor and viewer from the company www.brinno.com. I think that they have sent me already defective items, because nothing worked. I returned it on the next day and wrote the seller that it didn’t work. The seller told me that they would check these items and would provide the decision within several days. After this email, I haven’t received any reply, refund or new items. I’m absolutely sure that it has been the last time, when I have bought from them.